function y = flipMDL(model,arg)


switch arg,
    case 'Ox'
        for i=1:size(model,2),
            for j=1:size(model{i},3),
                model{i}(:,2,j) = -model{i}(:,2,j);
            end
        end
    case 'Oy'
        for i=1:size(model,2),
            for j=1:size(model{i},3),
                model{i}(:,1,j) = -model{i}(:,1,j);
            end
        end
    otherwise
        error('Unknown initialization method.');
end

    y = model;
end